1. Field Of The Invention
This invention relates generally to an arrangement for mounting an electric motor employed in driving a fan on a support barrier, and more specifically to provide a motor mounting arrangement that effectively reduces the torque vibrations imposed on the support barrier by the motor while eliminating lateral and longitudinal movement of the motor to maintain axial integrity of the shaft.
Due to their comparatively low cost it has become common practice to employ shaded pole induction motors for driving fans and blowers in room air conditioners. These motors, however, do not produce uniform torque for every position of the rotor. When shaded pole electric motors are employed in the capacity ranges used for driving room air conditioner fans and blowers, they characteristically produce torque pulses or vibrations of generally between 60 to 650 Hz. Motor torque vibration of those magnitudes cause hums or noise levels that are objectionable, this is especially true since air conditioners are generally used in living quarters and quite often are installed in sleeping areas.
The vibration dampening must be effective not only in controlling the noise level but as in the case of the present embodiment, when the motor is employed to drive a fan, axial integrity or lateral movement of the motor shaft from its rotational axis must be also controlled. In order to obtain high air moving efficiencies with a given fan size it is common practice to orient the fan in an orifice that is relatively close to the extreme ends of the fan blades. Accordingly the motor mounting arrangement while permitting vibration dampening movement must also prevent axial movement of the motor shaft to maintain design clearance and prevent contact between the fan and orifice during fan operation.
2. Description of the Prior Art
In some prior art attempts to minimize motor vibration, vibration isolating members are employed as described in U.S. Pat. No. 3,270,221--P. B. Shaffer. While the employment of such members is effective in isolating motor vibration they, however, permit lateral movement of the shaft relative to its rotational axis. Prior art attempts have also included incorporating resilient means on either end of a horizontally oriented electric motor as disclosed in U.S. Pat. No. 2,096,139--M. L. Spahr and in a vertically oriented electric motor as disclosed in U.S. Pat. No. 3,270,222 to P. B. Shaffer assigned to General Electric Company, assignee of the present invention.